Light emitting devices such as light emitting diodes (LED) have been prevalently applied nowadays. Generally, a light emitting device is driven by a corresponding driving apparatus, e.g., referring to FIG. 1, one end of the light emitting module 1 is provided a voltage VB for operation, while the other end is connected to a driving module 2 so as to be driven by the driving module 2.
FIG. 2 is another example of a light emitting device and a driving apparatus in the prior art, wherein the light emitting device is a LED array such as active matrix organic light emitting diode (AMOLED), while the driving apparatus is a driving current source module. In FIG. 2, the LED array has a plurality of LED strings, e.g., LED strings L11, L12, . . . , L1n-1 and L1n, and LED strings Lm1, Lm2, Lmn-1 and Lmn. Similar to FIG. 1, a boost module 3 provides voltage VB to each LED string, and each LED string is driven by driving current source modules 21, 22, . . . , 2m. 
On one hand, light emitting devices such as LED array often fail. FIGS. 3A and 3B show two categories of faults, wherein for the convenience of illustration, only one LED string is shown, while other LED strings are omitted. For example, with reference to FIG. 3A, one category of faults is that one end of the LED string connected in series with the driving current source module is grounded, which causes an uncontrollable driving current source module, and much worse, it will even damage the LED array and the driving current source module. The other category of faults is that an open circuit occurs in the LED string. For example, with reference to FIG. 3B, the open circuit (indicated with an “X”) occurs between the voltage VB provided by the boost module and the LED L11. It may be understood that the open circuit may also occur between for example L11 and L12, or L1n-1 and L1n, or L1n and the current source. The prior art always employs a complex and independent circuit module to detect the two categories of faults, which raises the cost and makes circuit design more complex. Therefore, there is a need for a driving apparatus which has a simple design and can detect at least a part of the above faults and a corresponding detecting method.
On the other hand, more and more LED applications require that the LED light be dimmable, which requires that the LED driver have different driving capabilities according to the needs so as to change the intensity of the light emitted by the LED. Besides, in a combination of LEDs emitting different colors of light, wherein different colors are mixed to obtain light with a particular light temperature, it is needed that drivers for LEDs of one or more colors can dim light. In a low-light state, a conventional LED driver generally uses a pulse width modulation (PWM) to dim light. At this point, delay always occurs between the PWM signal and the dimming current in the driver, which causes dimming delay, such that the driving current of the LED tends to be inaccurate, which causes the LED light to be overly dimmed and the brightness of the LED panel to be inaccurate. Therefore, a driving apparatus improving response and an improved method are desirable.